1. Field of the Invention
The present invention relates to an information processing device, an information processing method, a computer-readable recording medium, and an inspection system.
2. Description of the Related Art
Techniques for detecting distinguishing points (pixels) and regions within images, such as detection of abnormalities through appearance inspection of products or using monitoring cameras, have been already known. In conventional techniques for detecting distinctive points (pixels) and regions within images, a group of reference images that are normal are prepared in advance. A step that often follows this is calculating the difference between feature values, such as luminance values, of each pixel and a corresponding pixel in inspection target images and reference images to identify changes between images.
For example, Japanese Unexamined Patent Application Publication No. 2005-265661 proposes image inspection configured to statistically determine a normal range of luminance values in an inspection target image in appearance inspection of products, thereby being independent of an inspection operator. Japanese Unexamined Patent Application Publication No. 2013-160629 proposes a method in which averages and standard deviations of luminance values of corresponding pixels in the respective reference images are determined in advance. In the method, when inspection is then conducted, standard scores for respective pixels are obtained by subtracting the corresponding average values from luminance values in an inspection target image and then dividing results of the subtraction by the corresponding standard deviations, and a pixel the standard score of which is larger than a previously determined threshold is identified as an abnormal pixel.
However, the conventional techniques are disadvantageous in that abnormalities cannot be adequately detected when there is an error in positioning of an inspection target and there is a slight change in shape of an inspection target. Furthermore, the method in which standard scores are obtained using averages all over an image is disadvantageous in that a local abnormality cannot be detected in some cases because a locally existing abnormality acts as a noise component all over the image.